Except no cultured adult programmer would use the original PHP syntax for templating, unless it's some 5-minutes worth development script. It's too powerful and too complicated. People use smarty or twig, which are basically the same thing as Jinja.
I always liked TAL, it kind of made sense to me that the templating engine itself understands the syntax of the language you are templating. It ought to be impossible to write invalid HTML/XML. It's like the pain you get into when templating YAML with jinja, but if the YAML template also were itself a valid YAML file it would be much cleaner imho.
I don't disagree but we ended up with systems like Jinja because that's what people adopted. I also built GHRML which was a syntax aware template engine for generating XHTML documents and it never really took off.
Sometimes it's the simple and dumb solutions that win out over the cleaner stuff. Nowadays maybe less so, JSX clearly won and if you build UIs today that's probably what you should go for. However there were many solutions like JSX a long time before and somehow the value proposition was not right for the software written at the time.
